Rinse the cauliflower, finely chop in a food processor or mini-chopper and drain in a cloth (there should be 2/3 cup after the juice has been drained off).
Combine the oatmeal and flour. Grate the cheese. Combine all the ingredients and form into a solid mass. Roll out between two pieces of baking parchment. Pre-bake at 200°C for approximately 15 minutes.
Slice the shallots into wedges and sauté them in a little butter and honey. Peel the beetroot and thinly slice (a peeler works well). Cover the pizza with everything except the walnuts and oregano and bake at 180°C for approximately 5 to 7 minutes. Top with walnuts and oregano.